The off pun is rather awful, but it does have precedent, and is
more succinct.

Fixes a problem where the editor would always be 30 pixels smaller
than its set height.

The height is now set on the outer wrapper DIV again, and some
height: 100% tricks are used to make height information flow
both ways (inside-out in demo/resize.html mode, outside-in in
normal, fixed-height mode).

Closes #775

When exiting fullscreen: fallback on width and height set by css instead of recalculating, which was wrong anyway, when pressing F11 a couple of times the editor would decrease in width.

Removing dependency on jQuery, only allow `Esc` to *exit* full screen (rather than *toggle*), and changing class name to be consistent with CodeMirror class naming practices.

Since v2 is the canonical CodeMirror at this point

So that I can put other doc-related stuff there without polluting the
root dir.

It's tiny anyway, no need to force people to include yet another file.

Much nicer than onKeyEvent